Preparation and characterization of a new CdS-NiFe2O4/reduced graphene oxide photocatalyst and its use for degradation of methylene blue under visible light irradiation

In this paper, CdS nanoparticles as a visible light active photocatalyst were coupled by NiFe2O4 and reduced graphene oxide (rGO) to form CdS-NiFe2O4/rGO nanocomposite by facile hydrothermal methods. The CdS-NiFe2O4/rGO nanocomposite shows enhanced photocatalytic activity for the degradation of methylene blue (MB) under visible light illumination. In addition to improved photocatalytic performance, this prepared nanocomposite shows increased photostability and is magnetically separable from the aqueous media. The degradation rate constant (k(app)) of the optimized photocatalyst, i.e. CdS-NiFe2O4 (0.05)/rGO 25wt% nanocomposite, was higher than the corresponding CdS and NiFe2O4 nanoparticles by factors of 11.1 and 8.9, respectively. The synergistic interactions between CdS, NiFe2O4 and rGO lead to enhanced surface area, reduced aggregation of the nanoparticles, decreased the recombination of photogenerated electron-hole pairs, and increased the charge separation efficiency and effective electron-hole generation transfer. According to the obtained results, a proposed mechanism of the photodegradation of MB under visible light irradiation is finally mentioned.